Independent Design of Bandpass Filter and Out-of-Band Absorptive Extracted Pole Cavity Resonator Using Surface Mount Resistors

This article proposes a synthesis method called absorptive extracted pole (EP) resonator (AEPR), for reflective-type bandpass filters (BPFs). By introducing a parallel-connected conductance on the traditional EP resonator (EPR), the AEPR is capable of electromagnetic power absorbing. When placing the AEPR in reflective-type BPF circuits, it is possible to remove the stopband reflective signal within a particular frequency band. The AEPRs are operating independently of the BPF circuit. When the AEPRs are cascaded before a BPF, the AEPR can be seen as a matching load in the lower- or upper-stopband. Thus, a high electromagnetic power absorption rate
$\eta $
is achievable in the stopband. In addition, the bandwidth and resonating frequency of the AEPR are controlled by specific circuit elements. The frequency responses of the AEPR were analyzed theoretically. This novel AEPR is realized by a pair of
$H$
-plane metallic waveguide stubs. Two printed-circuit boards (PCBs) with surface mount device (SMD) resistor are installed at the end of the stubs, namely first stage AEPR. The stubs are dangling on the rectangular waveguide. First stage design and eighth stage cascaded design are presented as the application examples. The results obtained through simulation and measurement have validated the calculations conducted in this article.